Illumination system to eliminate laser speckle and projection system employing the same

Abstract

An illumination system designed to remove laser speckle and a projection system including the same. The illumination system includes a laser light source having at least one laser, a diffractive optical element to divide a laser beam emitted from the laser light source into a plurality of sub-beams and to periodically move in such a way as to temporally average the speckle of the laser beam, and an optical fiber bundle including a plurality of fibers with the same length to divide the sub-beams into smaller sub-beams. The illumination system divides the laser beam emitted from the laser light source into sub-beams and temporally or spatially averages the sub-beams, thereby effectively reducing or removing laser speckle. The projection system employing the illumination system can provide improved image quality.

1. An illumination system to remove speckle of a laser beam, the illumination system comprising:
 a laser light source having at least one laser to emit a laser beam; 
 a diffractive optical element to divide the laser beam emitted from the laser light source into a plurality of first sub-beams and to periodically move to temporally average the speckle of the laser beam; and 
 an optical fiber bundle including a plurality of fibers with the same length to divide the first sub-beams into smaller second sub-beams such that an image is formed according to the smaller second sub-beams. 
 
   
   
     2. The illumination system of  claim 1 , wherein each of the plurality of first sub-beams comprises a plurality of beamlets that are focused in an overlaying fashion on one another. 
   
   
     3. The illumination system of  claim 1 , wherein the diffractive optical element is rotatable with respect to the laser beam. 
   
   
     4. The illumination system of  claim 1 , further comprising:
 a beam-shaping unit to convert a cross-section of each of the second sub-beams into a predetermined shape. 
 
   
   
     5. An illumination system, comprising:
 a laser light source unit to emit a laser beam; 
 a movable temporal averaging unit to temporally average the laser beam emitted from the laser light source unit; and 
 an optical fiber bundle having a plurality of optical fibers each having the same length to divide the averaged laser beam emitted from the laser light source unit into a plurality of sub-beams so that an image is formed according to the sub-beams. 
 
   
   
     6. The illumination system of  claim 5 , wherein the movable temporal averaging unit comprises:
 a diffractive optical element to spatially average the laser beam emitted from the laser light source by dividing the laser beam into a plurality of overlapping beams; and 
 a driving unit to periodically move the diffractive optical element to temporally average the laser beam emitted from the laser light source. 
 
   
   
     7. A projection system to remove speckle of a laser beam, the projection system comprising:
 a laser light source having at least one laser to emit a laser beam; 
 a diffractive optical element to divide the laser beam emitted from the laser light source into a plurality of first sub-beams and to periodically move to temporally average the speckle of the laser beam; 
 an optical fiber bundle including a plurality of fibers with the same length to divide the first sub-beams into smaller second sub-beams; 
 a beam-shaping unit to shape the second sub-beams output by the optical fiber bundle; 
 a display device to produce an image using the second sub-beams shaped by the beam shaping unit; 
 a screen; and 
 a projection lens unit to enlarge and project the image onto the screen. 
 
   
   
     8. The projection system of  claim 7 , wherein each of the plurality of first sub-beams comprises a plurality of beamlets that are focused in overlaying fashion on one another. 
   
   
     9. The projection system of  claim 7 , wherein the diffractive optical element is ratable. 
   
   
     10. The projection system of  claim 7 , further comprising:
 a light path changer disposed between the beam-shaping unit and the display device.